Carbide/nitride coated cutting insert

ABSTRACT

A cutting insert of a substantially horizontal cylindrical segment shape is described. The cutting insert comprises top and bottom surfaces having a circular segment shape. The cutting insert further comprises a convex side. The cutting insert further comprises a flat side. The cutting insert further comprises a top cutting edge which is formed where the convex side and the top surface meet, and a bottom cutting edge which is formed where the convex side and the bottom surface meet. The cutting insert further comprises a hole extending from the convex side towards the flat side. The hole is positioned at a center of a surface of the flat side.

BACKGROUND Technical Field

The present disclosure is directed to cutting tools, and moreparticularly to a cutting insert adapted to be implemented in thecutting tools for machining a workpiece.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Metal machining cutting tools use cutting inserts made from qualitymaterials that can be operated at high speeds and handle rapid feedrates. Common shapes of cutting inserts include square, triangular andrhombus (diamond) providing four, three and two cutting edges,respectively, on each side of the insert. Conventional cutting insertshave straight cutting edges. In cutting operations, typically, a sharpand rough material is often left on workpiece edges after machiningprocess, known as “end-burr” or “exit-burr”, or sometimes simply as“burr”. For instance, in most metal drilling operations, burrs areformed as the drill exits the workpiece. Burr is an undesirableprojection of workpiece material at the edge of a machined surface.Formation of burr at the edge of a machined component may lead tomisalignment of assembled parts, unsafe conditions during handling ofmachined components, malfunctioning of the product during operation,etc.

Deburring is usually employed after cutting to remove burrs formedduring machining. Deburring consumes time and energy and hencenegatively affects productivity. Deburring is difficult to automate andis usually performed manually. In some instances, particularly forprecision parts, deburring and edge finishing can amount to as much as30 percent of the manufacturing time of the machined component.Moreover, known deburring operations have not been found to be fullysatisfactory to remove all interior burrs because of the differentconditions under which burrs are formed. Therefore, elimination orminimization of burr formation during machining operation itself isdesired for effectively reducing the need of the additional deburringprocess.

WO2021049786A1 describes a cutting insert that is interchangeablymounted in an insert pocket formed at an end portion of a cutting tooland is capable of cutting a workpiece, and having a cutting part whichmay include a first corner cutting edge formed to extend along a firstcorner side, which is one of the plurality of corner side parts, on aplane view; a first cutting edge formed to extend from one end of thefirst corner cutting edge in a convex curved shape along a pair of mainside surfaces; a second cutting edge formed to extend in a linear shapealong the pair of main side surfaces from one end of the first cuttingedge; a third cutting edge formed to extend from one end of the secondcutting edge to a convex curved shape having the same radius ofcurvature as the first cutting edge along the pair of main sidesurfaces. The design helps to enhance the stiffness of the cuttinginsert mounted in the insert pocket of the cutting tool and to smoothlyinducing the discharge of cutting chips. However, this reference doesnot disclose a reduction in burr formation.

U.S. Pat. No. 4,840,518A describes a disposable indexable cutting inserthaving opposed irregularly curved cutting edges and a smooth continuoustransition along each cutting edge and a corresponding radiused corneredge. The described cutting insert has been found to be particularlyuseful in the machining of titanium. However, this reference does notdisclose a reduction in burr formation.

DE2224529C2 describes a flat sided, regular polygon cutting insert formetal removal. The cutting insert has a convex cutting face surface inthe form of a frustum. This results in a cutting angle changing from alower value at corners to a higher value at the center of the cuttingedge. The reference discloses advantages when working hard surfaces andgives good shock loading resistance to the central cutting edge area.However, this reference does not disclose a reduction in burr formation.

DE10017645A1 describes a cutting insert, especially for millingcamshafts, having at least one cutting edge. The cutting edge iscomposed of a plurality of cutting edge sections that have the followinggeometrical allocations when viewed from a planar top perspective of theface adjoining the cutting edge: a first, straight section, a second,straight section that adjoins the first section and that includes anangle of more than 90° and less than 180° with said first section, and athird cutting edge section that is convexly curved and that adjoins theend of the second section facing away from the first section and whosecurved design, that may also consist of straight sub-sections offsetwith respect to one another, extends over an angular range of more than90°. The reference discloses that the contour of the cutting edgeensures that the same insert can be used several times. However, thisreference does not disclose a reduction in burr formation.

Each of the aforementioned references suffers from one or more drawbackshindering their adoption. Accordingly, it is an object of the presentdisclosure to provide a cutting insert that may help with attenuation ofburr, i.e., to decrease burr generation, during machining of metallicmaterials, and thus reduce the time and cost incurred in deburringprocesses and hence increase overall productivity.

SUMMARY

In one exemplary embodiment, a cutting insert of a substantiallyhorizontal cylindrical segment shape is described. The cutting insertincludes top and bottom surfaces having a circular segment shape. Thecutting insert further includes a convex side. The cutting insertfurther includes a flat side. The cutting insert further includes abottom cutting edge which is formed where the convex side and the bottomsurface meet. The cutting insert further includes a top cutting edgewhich is formed where the convex side and the top surface meet. Thecutting insert further includes a hole extending from the convex sidetowards the flat side, where the hole is positioned at a center of asurface of the flat side.

In some embodiments, the top and bottom surfaces are not parallel toeach other.

In some embodiments, the top and bottom cutting edges have a curvatureradius (R) ranging from about 4 mm to about 16 mm.

In some embodiments, the top and bottom cutting edges have a curvatureradius (R) ranging from about 6 mm to about 12 mm.

In some embodiments, the top and bottom cutting edges have a curvatureradius (R) of about 6 mm, about 8 mm, or about 12 mm.

In some embodiments, the top and bottom cutting edges have a curvatureradius (R) of about 6 mm.

In some embodiments, a length of the circular segment shape is about12.6 mm.

In some embodiments, the top and bottom cutting edges independently havea positive rake angle, or a negative rake angle.

In some embodiments, the top and bottom cutting edges each have thepositive rake angle.

In some embodiments, the top and bottom cutting edges each have apositive rake angle ranging from about 5 degrees to about 25 degrees.

In some embodiments, the top and bottom cutting edges each have apositive rake angle of about 20 degrees.

In some embodiments, the cutting insert has a clearance angle rangingfrom about 3 degrees to about 15 degrees.

In some embodiments, the cutting insert has a clearance angle of about 7degrees.

In some embodiments, a thickness of the cutting insert ranges from 2 mmto 20 mm, where the thickness is a longest distance between the flatside and the convex side, and the longest distance is perpendicular tothe flat side.

In some embodiments, the thickness of the cutting insert is about 4.75mm.

In some embodiments, the top and bottom cutting edges independently havea sharp edge or a round edge.

In some embodiments, the top and bottom cutting edges each have a sharpedge.

In some embodiments, the cutting insert comprises at least one hardmaterial selected from the group consisting of a carbide, a cementedcarbide, aluminum oxide, silicon nitride, cubic boron nitride, anddiamond.

In another exemplary embodiment, a cutting tool that contains the abovedescribed cutting insert is described. The cutting tool contains a toolbody having an insert mounting seat, and the cutting insert beingdetachably mounted on the insert mounting seat.

In some embodiments, the cutting tool further includes an insert holder,where the insert holder has a lateral mating surface complementary tothe hole of the cutting insert, and the cutting insert is detachablymounted on the insert mounting seat via the insert holder.

The foregoing general description of the illustrative embodiments andthe following detailed description thereof are merely exemplary aspectsof the teachings of this disclosure, and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of this disclosure and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1A is a perspective view of a conventional cutting insert.

FIG. 1B is an enlarged view of a portion ‘A’ of the conventional cuttinginsert as shown in FIG. 1A.

FIG. 2A is an exemplary illustration of a machining operation in whichthe conventional cutting insert of FIG. 1A, specifically the portion ‘A’thereof, is implemented for machining a workpiece.

FIG. 2B is an exemplary illustration of burr formation during themachining operation using the conventional cutting insert of FIG. 1A.

FIG. 2C is an exemplary illustration of a simulation depicting Von Misesstresses during the machining operation using the conventional cuttinginsert of FIG. 1A.

FIG. 3A is a perspective view of a cutting insert, according to certainembodiments.

FIG. 3B is a front view of the cutting insert of FIG. 3A, according tocertain embodiments.

FIG. 3C is a side view of the cutting insert of FIG. 3A, according tocertain embodiments.

FIG. 3D is an enlarged view of a portion ‘B’ of the cutting insert asshown in FIG. 3A, according to certain embodiments.

FIG. 3E is an enlarged view of a portion ‘C’ of the cutting insert asshown in FIG. 3A, according to certain embodiments.

FIG. 4A is an exemplary illustration of a machining operation in whichthe cutting insert of FIG. 3A, specifically the portion ‘C’ thereof, isimplemented for machining a workpiece, according to certain embodiments.

FIG. 4B is an exemplary illustration of possible burr formation duringthe machining operation using the cutting insert of FIG. 3A, accordingto certain embodiments.

FIG. 4C is an exemplary illustration of a simulation depicting Von Misesstresses during the machining operation using the cutting insert of FIG.3A, according to certain embodiments.

FIG. 5 is a perspective view of a cutting tool employing the cuttinginsert of FIG. 3A, according to certain embodiments.

FIG. 6 is an exemplary graph depicting comparative quantification ofburr formation for a straight cutting edge and convex-shaped cuttingedges of different curvatures, according to certain embodiments.

DETAILED DESCRIPTION

In the drawings, like reference numerals designate identical orcorresponding parts throughout the several views. Further, as usedherein, the words “a,” “an” and the like generally carry a meaning of“one or more,” unless stated otherwise.

Furthermore, the terms “substantially,” “approximately,” “approximate,”“about,” and similar terms generally refer to ranges that include theidentified value within a margin of 20%, 10%, or preferably 5%, and anyvalues therebetween.

As used herein, the words “substantially,” “approximately,”“approximate,” and “about” may be used when describing magnitude and/orposition to indicate that the value and/or position described is withina reasonable expected range of values and/or positions. For example, anumeric value may have a value that is ±1% of the stated value (or rangeof values), ±2% of the stated value (or range of values), ±5% of thestated value (or range of values), ±10% of the stated value (or range ofvalues), ±15% of the stated value (or range of values), or ±20% of thestated value (or range of values).

According to a first aspect, the present disclosure relates to a cuttinginsert for a cutting tool.

As used herein, cutting inserts are attachments to cutting tools formachining work pieces. Cutting inserts typically are replaceableattachments that have at least one cutting edge.

The cutting insert of the present disclosure has a substantiallyhorizontal cylindrical segment shape, in which one or more cutting edgesare formed at an intersection of a convex side and a generally planarsurface. Unlike commercially available cutting inserts that havestraight cutting edges, the presently disclosed cutting insert withconvex-shaped cutting edges helps to decrease generation of end-burrduring machining of metallic materials. As such, the present cuttinginsert helps to reduce the duration and cost of subsequent deburringprocesses and increases efficiency of machining operations.

Referring to FIG. 1A, a perspective view of a conventional cuttinginsert 100 is illustrated. The conventional cutting insert 100 is shownto be a square shaped cutting insert with multiple straight cuttingedges 102. In other examples, the conventional cutting insert 100 may betriangular-shaped or rhombus-shaped, which also traditionally includesone or more straight cutting edges. Typically, a portion of theconventional cutting insert 100 including one of the cutting edges 102is in contact with a workpiece to perform the cutting operation, such asa portion ‘A’ of the conventional cutting insert 100 as shown in FIG.1A. Referring to FIG. 1B, an enlarged view of the portion ‘A’ of thecutting edge 102 of the conventional cutting insert 100 is illustrated.As may be seen from FIG. 1B, the cutting edge 102 (in the presentexample, bottom cutting edge) is defined at an intersection of a frontsurface and a bottom surface of the conventional cutting insert 100.With the front surface and the bottom surface of the conventionalcutting insert 100 being generally orthogonal to each other, as shown inFIG. 1B, the cutting edge 102 of the conventional cutting insert 100 isa straight cutting edge.

Referring to FIG. 2A, the conventional cutting insert 100, orspecifically the portion ‘A’ thereof, is illustrated to be implementedfor performing a machining operation on a workpiece 200. In theillustration of FIG. 2A, the machining operation is shown to be anorthogonal cutting operation being performed on the workpiece 200, aswidely utilized in industrial processes, using the conventional cuttinginsert 100. For this purpose, as shown, the cutting insert 100 isoriented and positioned such that the cutting edge 102 of the cuttinginsert 100 is in contact with a section 202 of the workpiece 200.Specifically, the cutting edge 102 of the cutting insert 100 enters andexits through a region corresponding to the section 202 (as shown inFIG. 2A) of the workpiece 200, with the section 202 being located belowa segment 204 of the workpiece 200 of certain thickness.

Referring to FIG. 2B, as shown, during the machining operation, thesegment 204 of the workpiece 200, as defined by the section 202, isremoved from the workpiece 200 in the form of chip 206 being carved outof the workpiece 200. Further, as shown in FIG. 2B, a portion or apiece, usually a sharp and rough material, known as burr (represented byreference numeral 208), may be formed on the workpiece 200 as remains ofthe segment 204 that is left on the workpiece 200 during the machiningoperation. The burr 208 is typically formed at an edge of the section202 of the workpiece 200 from which the cutting edge 102 exits after themachining operation. With the machining operation using the conventionalcutting insert 100 (as described) with straight cutting edge 102, theburr 208 has a significant thickness, represented as thickness ‘t’ inthe illustration of FIG. 2B, which is undesirable, and thus needs to beremoved using deburring processes which adds to time and cost of themachining operation.

Further, FIG. 2C is an exemplary illustration of a simulation of the VonMises stresses (S. Mises) encountered by the conventional cutting insert100 during the machining operation. As shown, during the machiningoperation, the conventional cutting insert 100 may face significant VonMises stresses (S. Mises), specifically in a region ‘X’ corresponding tothe cutting edge 102. A Von Mises stress is a value that determines if agiven material may yield or fracture. A high concentration of the VonMises stress as shown at the cutting edge 102 suggests that theconventional cutting insert 100 may be prone to material failure in agiven machining operation.

As defined herein, a horizontal cylindrical shape may be represented bya solid obtained by cutting a horizontal cylinder with a radius r by asingle plane oriented perpendicular to circular planar ends of thehorizontal cylinder. Preferably, when the cut makes a height h above thebottom of the horizontal cylinder, h is no greater than r.

Referring now to FIGS. 3A-3C, different views of a cutting insert 300are illustrated. Further referring to FIGS. 3D and 3E, in combinationwith FIGS. 3A-3C, enlarged views of portions ‘B’ and ‘C’ respectively ofthe cutting insert 300 are illustrated. The cutting insert 300 of thepresent disclosure has a design that helps with attenuation of burrformation during machining of metallic materials. As may be seen, thecutting insert 300 has a substantially horizontal cylindrical segmentshape. In some embodiments, the cutting insert 300 has a hemicylindricalshape. Such shapes for the cutting insert 300 may be achieved by a solidcut from a cylinder of certain length and certain radius by a singleplane oriented parallel to the axis of symmetry of such cylinder. Thecutting insert 300 of the present disclosure is formed of hard materialto allow the cutting insert 300 to be used for machining operations. Inan aspect of the present disclosure, the cutting insert 300 includes atleast one hard material selected from the group consisting of a carbide,a cemented carbide, aluminum oxide, silicon nitride, cubic boronnitride, and diamond. That is, the cutting insert 300 may be formedusing one or more of carbide, cemented carbide, aluminum oxide, siliconnitride, cubic boron nitride, and diamond. In some examples, the cuttinginsert 300 may be provided with coatings which may help to increase wearresistance and operational life thereof. Coatings for the cutting insert300 may include, but not limited to, titanium nitride, titaniumcarbonitride, titanium aluminum nitride, aluminum titanium nitride,aluminum oxide, chromium nitride, zirconium nitride, and diamond DLC(Diamond-like carbon).

As illustrated, the cutting insert 300 includes top and bottom surfaces302, 304 having a circular segment shape. With the cutting insert 300having the substantially horizontal cylindrical segment shape, the topsurface 302 and the bottom surface 304 may correspond to planar ends ofthe cylinder from which the cutting insert 300 may be formed. Herein,the circular segment shape refers to a two-dimensional surface that isbounded by an arc corresponding to periphery of the sides of thecylinder and by a chord corresponding to an edge of plane orientedparallel to the axis of symmetry of the cylinder from which the cuttinginsert 300 may be formed. The cutting insert 300 further includes aconvex side 306. Again, with the cutting insert 300 having thesubstantially horizontal cylindrical segment shape, the convex side 306may correspond to outer surface of the cylinder from which the cuttinginsert 300 may be formed. The cutting insert 300 further includes a flatside 308. Yet again, with the cutting insert 300 having thesubstantially horizontal cylindrical segment shape, the flat side 308may correspond to the planar end parallel to the axis of symmetry of thecylinder from where the cutting insert 300 may have been cut.

In the present configuration, a thickness (W) of the cutting insert 300is defined as a longest distance between the flat side 308 and theconvex side 306. The longest distance is considered to be a line fromthe flat side 308 to periphery of the convex side 306 of the cuttinginsert 300, with such line being perpendicular to the flat side 308. Asbetter illustrated in FIG. 3A, the thickness (W) corresponds to asagitta (height) of the circular segment shape of the top surface 302(or the bottom surface 304). In particular, the thickness (W) maycorrespond to the sagitta (height) of larger of the circular segmentshape of the top surface 302 and the bottom surface 304. In an aspect ofthe present disclosure, the thickness (W) of the cutting insert 300ranges from 2 mm to 20 mm, preferably from 2.5 mm to 15 mm, preferablyfrom 3 mm to 10 mm, preferably from 4 mm to 8 mm, preferably from 4.5 mmto 6 mm. In a specific aspect of the present disclosure, the thicknessof the cutting insert 300 is about 4.75 mm. Further, with the top andbottom surfaces 302, 304 having the circular segment shape, the curvedarcs of the top and bottom surfaces 302, 304 (at the convex side 306) ofthe cutting insert 300 may be limited by an arc length, or simply length(L). Herein, the length (L) is defined as the distance between endpointsof the circular segment shapes of the top and bottom surfaces 302, 304.In an aspect of the present disclosure, the length (L) of the circularsegment shape is about 12.6 mm.

Further, in an aspect of the present disclosure, as better shown in FIG.3C, the top and bottom surfaces 302, 304 are not parallel to each other.That is, the top surface 302 and the bottom surface 304 of the cuttinginsert 300 may be formed such that at least one of the top and bottomsurfaces 302, 304 may be angled other than 90 degrees with respect tothe flat side 308. For instance, the cutting insert 300 may be formed asa horizontal cylindrical wedge (as known in the art) to have theconfiguration with the top and bottom surfaces 302, 304 not beingparallel to each other. In an example, one of the top surface 302 andthe bottom surface 304 may be tilted with respect to the flat side 308.In another example, both the top surface 302 and the bottom surface 304may be tilted with respect to the flat side 308, either along samerotational direction (with different inclinations) or differentrotational directions without any limitations. Such configuration forthe cutting insert 300 may help to define a clearance angle therefor, aswill be discussed later in the description.

Further, as illustrated, the cutting insert 300 includes a bottomcutting edge 312. The bottom cutting edge 312 is formed where the convexside 306 and the bottom surface 304 meet. With the bottom cutting edge312 being formed at intersection of the planar bottom surface 304 andthe convex side 306 of the cutting insert 300, the bottom cutting edge312 is defined as a convex-shaped cutting edge in the cutting insert300; in contrast to straight cutting edge (such as the cutting edge 102)in the conventional cutting insert 100. The cutting insert 300 may alsoinclude a top cutting edge 314. The top cutting edge 314 is formed wherethe convex side 306 and the top surface 302 meet. Similar to the bottomcutting edge 312, with the top cutting edge 314 being formed atintersection of the planar top surface 302 and the convex side 306 ofthe cutting insert 300, the top cutting edge 314 is also defined as aconvex-shaped cutting edge in the cutting insert 300; in contrast tostraight cutting edge (such as the cutting edge 102) in the conventionalcutting insert 100.

In an example, the top and bottom cutting edges 314, 312 independentlyhave a sharp edge or a round edge. In an alternate example, the top andbottom cutting edges 314, 312 each have a sharp edge. That is, in oneexample, the top and bottom cutting edges 314, 312 may both be sharpedges; and in other example, both the top and bottom cutting edges 314,312 may be round edges; and in still other example, one of the top andbottom cutting edges 314, 312 may be round edge and other be sharp edgewithout any limitations. It may be appreciated by a person skilled inthe art that whether a given edge is a sharp edge or a round edge may bedefined by its tool edge radius. It may be understood that the tool edgeradius significantly affects cutting forces required, cutting friction,tool wear, material deformation, and a variety of machining performancemeasures during machining operations. Therefore, it may be important toconsider the tool edge radius, i.e., whether the top and bottom cuttingedges 314, 312 may be the sharp edge or the round edge, for the cuttinginsert 300 depending on the type and requirements of machining operationto be performed thereby.

With the bottom cutting edge 312 and the top cutting edge 314 beingconvex-shaped cutting edges in the cutting insert 300, each of the topand bottom cutting edges 314, 312 defines a curvature radius (R) (asshown in FIG. 3E). Herein, the curvature radius (R) is the radius ofcurvature which is equal to a radius of a circular arc which bestapproximates the curve defined by the top and bottom cutting edges 314,312. In the present examples, the bottom cutting edge 312 and the topcutting edge 314 may have an equal curvature radius (R) or differentrespective curvature radiuses (R) without any limitations. In an aspectof the present disclosure, the top and bottom cutting edges 314, 312have a curvature radius (R) ranging from about 4 mm to about 16 mm,preferably from about 5 mm to about 15 mm, preferably from about 6 mm toabout 14 mm, preferably from about 7 mm to about 13 mm, preferably fromabout 8 mm to about 12 mm, preferably from about 9 mm to about 10 mm. Ina specific aspect of the present disclosure, the top and bottom cuttingedges 314, 312 have the curvature radius (R) ranging from about 6 mm toabout 12 mm, preferably from about 7 mm to about 11 mm, preferably fromabout 8 mm to about 10 mm. In a more specific aspect of the presentdisclosure, the top and bottom cutting edges 314, 312 have the curvatureradius (R) of about 6 mm, about 8 mm, or about 12 mm. That is, the topand bottom cutting edges 314, 312 have the respective curvature radius(R) value from one of about 6 mm, about 8 mm, or about 12 mm. In acertain aspect of the present disclosure, the top and bottom cuttingedges 314, 312 have the curvature radius (R) of about 6 mm. It may beappreciated by a person skilled in the art, that the value(s) of thecurvature radius (R) for the top and bottom cutting edges 314, 312 maybe defined based the application and requirement of the cutting insert300 for a given machining operation.

Also, it may be appreciated that geometry of the cutting insert 300 isan important factor that determines ease and performance of machiningoperation thereby. Primarily, the geometry of the cutting insert 300 isdefined by its clearance angle (γ) and its rake angle (α). Asillustrated in FIG. 3C, the cutting insert 300 defines the clearanceangle (γ) therefor which is generally defined as an angle between aprincipal flank surface of the cutting insert 300, which in this casemay be the top surface 302 or the bottom surface 304 depending on whichof the top cutting edge 314 or the bottom cutting edge 312 is beingemployed for performing the cutting operation, and cutting direction(generally, horizontal plane). Further, as illustrated in FIG. 3D, thecutting insert 300 defines the rake angle (α) therefor. The rake angle(α) is defined as an angle of orientation of tool's rake surface, whichin this case is the orientation of the convex side 306, from thereference plane (generally, vertical plane).

In an aspect of the present disclosure, the cutting insert 300 has theclearance angle (γ) ranging from about 3 degrees to about 15 degrees,preferably from about 5 degrees to about 12 degrees, more preferablyfrom about 6 degrees to about 10 degrees. In a specific aspect of thepresent disclosure, the cutting insert 300 has the clearance angle (γ)of about 7 degrees.

Further, in an aspect of the present disclosure, the top and bottomcutting edges 314, 312 independently have a positive rake angle (α), ora negative rake angle (α). It may be noted that depending on theinclination/elevation of rake surface from the reference plane, the rakeangle (α) may have either positive or negative, or even zero value. Withpositive rake angle (α), the cutting insert 300 requires less cuttingforce and thus lower power requirement for the machining operation, andalso results in less chip deformation during the machining operation;however, operational life of the employed cutting edge 312, 314 thereinis reduced. On the other hand, with negative rake angle (α), the cuttinginsert 300 offers a strong tool tip which makes the employed cuttingedge 312, 314 more resilient under impact loading; however, sheardeformation of the chip becomes higher and thus higher cutting force maybe required during the machining operation. In a preferred aspect of thepresent disclosure, the top and bottom cutting edges 314, 312 each havea positive rake angle (α). In a specific aspect of the presentdisclosure, the top and bottom cutting edges 314, 312 each have apositive rake angle (α) ranging from about 5 degrees to about 25degrees, preferably from about 10 degrees to about 23 degrees, morepreferably from about 15 degrees to about 22 degrees, or about 20degrees. In a more specific aspect of the present disclosure, the topand bottom cutting edges 314, 312 each have a positive rake angle (α) ofabout 18 degrees.

Referring now to FIG. 4A, the cutting insert 300, or specifically theportion ‘C’ thereof, is illustrated to be implemented for performing amachining operation on a workpiece 400. In the illustration of FIG. 4A,the workpiece 400 is shown to be a generally cuboidal block; however, itmay be appreciated that the workpiece 400 may be of any other shapewhich needs to undergo machining operation. Further, the machiningoperation is shown to be an orthogonal cutting operation being performedon the workpiece 400, as widely utilized in industrial processes, usingthe cutting insert 300; however, the machining operation should not belimited to orthogonal cutting operation and in other examples, themachining operation may include other suitable cutting operation, suchas drilling operation without any limitations. For performing machiningoperation, as shown, the cutting insert 300 is oriented and positionedsuch that the cutting edge, specifically the bottom cutting edge 312, ofthe cutting insert 300 is in contact with a section 402 of the workpiece400. Although the present example has been described in terms of themachining operation being performed by the bottom cutting edge 312 ofthe cutting insert 300; in other example, the top cutting edge 314 ofthe cutting insert 300 may be implemented for performing the describedmachining operation and same results may be achieved without departingfrom the spirit and the scope of the present disclosure. Specifically,as shown in FIG. 4A, the bottom cutting edge 312 of the cutting insert300 enters and exits through a region corresponding to the section 402(as shown in FIG. 4A) of the workpiece 400, with the section 402 beinglocated below a segment 404 of the workpiece 400 of certain thickness.

Referring to FIG. 4B, as shown, during the machining operation, thesegment 404 of the workpiece 400, as defined by the section 402, isremoved from the workpiece 400 in the form of chip 406 being carved outof the workpiece 400. Further, as shown in FIG. 4B, a portion or apiece, usually a sharp and rough material, known as burr (represented byreference numeral 408), may possibly be formed on the workpiece 400 asremains of the segment 404 that is left on the workpiece 400 during themachining operation. It may be noted that the burr 408 is also referredto as “exit-burr” or “end-burr” in the art, with such terms beinginterchangeably used without any limitations. The burr 408 may be formedat an edge of the section 402 of the workpiece 400 from which the bottomcutting edge 312 exits after the machining operation. With the currentmachining operation, as illustrated in FIG. 4B, using the convex-shapedcutting edge 312 of the present cutting insert 300, the possibly formedburr 408 has a significantly reduced thickness (represented as thickness‘T’ in the illustration of FIG. 4B) compared to the thickness ‘t’ of theburr 208 (as shown in FIG. 2B) formed during the machining operationusing the straight cutting edge 102 of the conventional cutting insert100.

Further, FIG. 4C is an exemplary illustration of a simulation of the VonMises stresses (S. Mises) encountered by the cutting insert 300 of thepresent disclosure during the machining operation. As shown, during themachining operation, the cutting insert 300 may face comparatively lowerVon Mises stresses (S. Mises) at its cutting edge, such as the bottomcutting edge 312, compared to the conventional cutting insert 100 (asdepicted in FIG. 2C). As discussed above, since the Von Mises stress isa value used to determine if a given material may yield or fracture,with lower concentration of the Von Mises stress at the cutting edge 312(as shown), the present cutting insert 300 is less prone to materialfailure in a given machining operation.

Further, as illustrated in FIGS. 3A-3C, the cutting insert 300 includesa hole 310 extending from the convex side 306 towards the flat side 308.That is, the hole 310 is defined to be extending from the convex side306 through the flat side 308. The hole 310 may be formed by drilling ofa through-hole in the cutting insert 300, extending from the convex side306 through the flat side 308. In an aspect, the hole 310 is positionedat a center of a surface of the flat side 308. In an example, the centerof the surface of the flat side 308 may be a diagonal center of thesurface of the flat side 308.

According to another aspect, the present disclosure relates to a cuttingtool that includes a tool body having an insert mounting seat, and thecutting insert of the first aspect being detachably mounted on theinsert mounting seat. In some embodiments, the cutting tool may furtherinclude an insert holder. Preferably, the insert holder has a lateralmating surface complementary to the hole 310 of the cutting insert, andthe cutting insert is detachably mounted on the insert mounting seat viathe insert holder. As such, the hole 310 may be utilized to support thecutting insert 300 in a cutting tool. For instance, the present cuttinginsert 300 may be mounted onto an insert holder (e.g., a shaft) of thecutting tool, by passing the said insert holder (e.g., the shaft)through the hole 310 and securing the cutting insert 300 thereto byusing a fastener.

FIG. 5 is a perspective view of an exemplary cutting tool 500 employingthe cutting insert 300. As shown, the cutting tool 500 has a tool body502. The tool body 502 provides an insert mounting seat 504. Further, asshown, the cutting insert 300 is detachably mounted on the insertmounting seat 504. A top side 506 of the tool body 502 is embodied witha face extension 508 for the cutting insert 300, which runs upward in acurved manner and helps with chip disposal. Also, as shown, the cuttingtool 500 includes an insert holder 510. The insert holder 510 has alateral mating surface 512 complementary to the hole 310 of the cuttinginsert 300.

The cutting insert 300 is detachably mounted on the insert mounting seat504 via the insert holder 510. In the illustrated example, the insertholder 510 is shown in the form of a clamping screw. However, inaddition to the clamping screw, other insert holders for fasteningpurposes may also be used in the cutting tool.

FIG. 6 is an exemplary graph 600 depicting comparative quantification ofburr formation for a straight cutting edge and convex-shaped cuttingedges of different curvatures. The graph 600 represents burr formation(in millimeters (mm)) along vertical axis and workpiece exit edge (inmillimeters (mm)) along horizontal axis. In the graph 600, approximately70% of the workpiece exit length is being considered. As shown, in anideal machining operation, the workpiece exit edge may have zero burrformation. As may be seen from the graph 600, for a straight cuttingedge (such as the cutting edge 102 in the conventional cutting insert100), the end burr is higher than 0.055 mm for the workpiece exit edgeof about 1 mm to 3 mm. Further, as may be seen from the graph 600, forconvex-shaped cutting edges (such as the cutting edge 312, 314 in thecutting insert 300 of the present disclosure) for each of the employedcurvatures (R), the end burrs are significantly lower compared to thestraight cutting edge. For example, for the convex-shaped cutting edgewith the curvature radius (R) of about 12 mm, the end burr is about0.0475; for the convex-shaped cutting edge with the curvature radius (R)of about 8 mm, the end burr is about 0.0450; and for the convex-shapedcutting edge with the curvature radius (R) of about 6 mm, the end burris about 0.0425. It may be noted that in each of the given examples, theend burr formation in the convex-shaped cutting edges as described forthe cutting insert 300 of the present disclosure is significantly lowercompared to the straight cutting edge of the conventional cutting insert100.

It may be appreciated that the machining operations, particularly whenthe casting is formed of nonferrous material, such as an aluminum or amagnesium alloy, result in the formation of burrs at the intersectionsof the passages. Such burrs needs to be completely removed before thedevice is assembled and placed in use, because the burrs are subject tobreak away in course of use, and may possibly enter a fluid line, wherethey may cause serious damage by blocking fluid flow through restrictedports, etc., or become lodged in the path of moving parts of the device.It has been suggested that the cause of burrs remaining is that theforce to bend a small portion of the workpiece adjacent to the edgeexceeds the shearing force to cut off the portion, and that the smallportion of the workpiece being bent by the cutting edge of the cutterinsert toward the feeding direction of the face milling cutter prior tobeing cut off thoroughly by the cutting edge. The proposed convex-shapedcutting insert 300 of the present disclosure, instead of straight-edgecutting insert 100 (that are commercially available and commonly used inmachining processes), due to its unique shape of the cutting edge 312,314, may help to decrease the end-burr generation during machining ofmetallic materials, and thus reduce the time and cost incurred indeburring processes and hence increase productivity by curtailing thetime, cost and energies incurred in deburring processes. Moreover, thepresent cutting insert 300 would be beneficial in decreasing totalenergy foot-print in the overall machining operation.

The embodiment of the present disclosure is illustrated with respect toFIG. 3A through FIG. 6 . One embodiment describes the cutting insert 300of the substantially horizontal cylindrical segment shape. The cuttinginsert 300 comprising the top and bottom surfaces 302, 304 having thecircular segment shape; the convex side 306; the flat side 308; the topcutting edge 314 which is formed where the convex side 306 and the topsurface 302 meet; the bottom cutting edge 312 which is formed where theconvex side 306 and the bottom surface 304 meet; and the hole 310extending from the convex side 306 towards the flat side 308, where thehole 310 is positioned at the center of the surface of the flat side308.

The cutting insert 300, wherein the top and bottom surfaces 302, 304 arenot parallel to each other.

The cutting insert 300, wherein the top and bottom cutting edges 314,312 have the curvature radius (R) ranging from about 4 mm to about 16mm. The cutting insert 300, wherein the top and bottom cutting edges314, 312 have the curvature radius (R) ranging from about 6 mm to about12 mm. The cutting insert 300, wherein the top and bottom cutting edges314, 312 have the curvature radius (R) of about 6 mm, about 8 mm, orabout 12 mm. The cutting insert 300, wherein the top and bottom cuttingedges 314, 312 have the curvature radius (R) of about 6 mm. In someembodiments, the cutting insert 300, wherein the length (L) of thecircular segment shape is ranging from about 8 to about 16 mm,preferably from about 10 to about 14 mm, more preferably from about 12to about 13 mm, or about 12.6 mm.

The cutting insert 300, wherein the top and bottom cutting edges 314,312 independently have the positive rake angle (α), or the negative rakeangle (α). The cutting insert 300, wherein the top and bottom cuttingedges 314, 312 each have the positive rake angle (α). The cutting insert300, wherein the top and bottom cutting edges 314, 312 each have thepositive rake angle (α) ranging from about 5 degrees to about 25degrees. The cutting insert 300, wherein the top and bottom cuttingedges 314, 312 each have the positive rake angle (α) of about 20degrees. The cutting insert 300, which has the clearance angle (γ)ranging from about 3 degrees to about 15 degrees. The cutting insert300, which has the clearance angle (γ) of about 7 degrees.

The cutting insert 300, wherein the thickness (W) of the cutting insert300 ranges from 2 mm to 20 mm, wherein the thickness (W) is the longestdistance between the flat side 308 and the convex side 306, and thelongest distance is perpendicular to the flat side 308. The cuttinginsert 300, wherein the thickness (W) of the cutting insert 300 is about4.75 mm.

The cutting insert 300, wherein the top and bottom cutting edges 314,312 independently have the sharp edge or the round edge. The cuttinginsert 300, wherein the top and bottom cutting edges 314, 312 each havethe sharp edge.

The cutting insert 300, comprising at least one hard material selectedfrom the group consisting of the carbide, the cemented carbide, aluminumoxide, silicon nitride, cubic boron nitride, and diamond.

Another embodiment describes the cutting tool 500 including the toolbody 502 having an insert mounting seat 504, and the cutting insert 300being detachably mounted on the insert mounting seat 504.

The cutting tool may further include the insert holder 310, where theinsert holder 310 has the lateral mating surface 512 complementary tothe hole 310 of the cutting insert 300, and the cutting insert 300 isdetachably mounted on the insert mounting seat 504 via the insert holder310.

Obviously, numerous modifications and variations of the presentdisclosure are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A coated cutting insert for machining a metal workpiece, comprising:at least one coated surface, wherein the coating is at least oneselected from the group consisting of a carbide and a nitride; top andbottom surfaces having a circular segment shape; a convex side; a flatside; a top cutting edge which is formed where the convex side and thetop surface meet; a bottom cutting edge which is formed where the convexside and the bottom surface meet; and a hole extending from the convexside towards the flat side, wherein the hole is positioned at a centerof a surface of the flat side, wherein the coated cutting insert has ahemicylindrical shape with a planar inset on the convex side, a plane ofthe planar inset being parallel to a plane of the flat side, wherein theconvex side includes a convex surface portion that extends radiallybeyond the planar inset on the convex side, wherein the top and bottomsurfaces are not parallel to each other, wherein the top and bottomcutting edges have a curvature radius (R) in a range of from 4 mm to 16mm, and wherein the top and bottom cutting edges each have a positiverake angle in a range of from 5 to 25°. 2-3. (canceled)
 4. The coatedcutting insert of claim 1, wherein the top and bottom cutting edges havea curvature radius (R) is in a range of from 6 mm to 12 mm.
 5. Thecoated cutting insert of claim 1, wherein the top and bottom cuttingedges have a curvature radius (R) of 6 mm.
 6. The coated cutting insertof claim 1, wherein the top and bottom cutting edges have a curvatureradius (R) of 8 mm.
 7. The coated cutting insert of claim 6, wherein alength of the circular segment shape is 12.6 mm.
 8. The coated cuttinginsert of claim 1, wherein the top and bottom cutting edgesindependently have a positive rake angle, or a negative rake angle. 9.The coated cutting insert of claim 8, wherein the top and bottom cuttingedges each have the positive rake angle.
 10. (canceled)
 11. The coatedcutting insert of claim 1, wherein the top and bottom cutting edges eachhave a positive rake angle of 20°.
 12. The coated cutting insert ofclaim 1, which has a clearance angle in a range of from 3 to 15°. 13.The coated cutting insert of claim 12, which has a clearance angle of7°.
 14. The coated cutting insert of claim 1, wherein a thickness of thecoated cutting insert is in a range of from 2 mm to 20 mm, wherein thethickness is a longest distance between the flat side and the convexside, and the longest distance is perpendicular to the flat side. 15.The coated cutting insert of claim 14, wherein the thickness of thecoated cutting insert is 4.75 mm.
 16. The coated cutting insert of claim1, wherein the top and bottom cutting edges independently have a sharpedge or a round edge.
 17. The coated cutting insert of claim 16, whereinthe top and bottom cutting edges each have a sharp edge.
 18. The coatedcutting insert of claim 1, comprising a carbide, a cemented carbide,aluminum oxide, silicon nitride, cubic boron nitride, and/or diamond.19. A cutting tool, comprising: a tool body having an insert mountingseat; and the coated cutting insert of claim 1 being detachably mountedon the insert mounting seat.
 20. The cutting tool of claim 19, furthercomprising: an insert holder, wherein the insert holder has a lateralmating surface complementary to the hole of the coated cutting insert,and wherein the coated cutting insert is detachably mounted on theinsert mounting seat via the insert holder.